The present general inventive concept is directed to signal processing and signal signature detection particularly to determine the presence and/or type of activity in the region of interest. For example, the present general inventive concept may implement means by which the use particular devices in a particular area, structure, vehicle, etc., can be detected and identified, as well as identifying individuals that may be operating such devices. Whereas systems for activity detection and surveillance may exist in various forms, such systems are typically configured to detect and identify a limited number of conditions and/or activities and do so typically by direct observation or measurement of the activity. Moreover, certain related systems typically implement sensors to detect only a few forms of energy so as to minimize computational resources needed to evaluate a broad range of energy forms. The present general inventive concept overcomes the limitations in the related art through, among other things, robust data reduction techniques through which signals corresponding to a wide range of energy modalities can be, among other things, identified, classified, compared and correlated. Moreover, the signals used to determine device use and/or activity may be obtained from energy incidental to the device use and/or activity without specifically instrumenting or directly observing each activity, each device or actor.